Core-Shell Acrylic Adhesive Emulsion for Fast-Setting Bonds

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Solution Overview

Problem

The furniture industry lacks an aqueous-based, one-part adhesive that is free from halogenated polymers and natural rubbers, which are often associated with skin allergies and requires additives for stability, and needs to provide fast-setting bonds with sufficient handling strength without the use of coagulants or strong alkalis.

Innovation Solution

Development of a core-shell polymeric adhesive emulsion with a pH of 6.5 or less, comprising a non-reactive polymeric core and a polymeric shell with pendent functional groups, which can be externally crosslinked to achieve fast-setting properties without the need for coagulants or strong alkalis, allowing for repositionability and re-bondability of substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional organic solvent-based contact adhesives are used, then fast-setting performance is achieved, but environmental safety and user health are compromised due to harmful solvents and additives

Engineering Contradiction:
Improveharmful additivesVSAvoidsetting speed
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent changes the chemical composition parameters by using acrylic polymer emulsion instead of organic solvents, and by carefully controlling pH (3.0-6.5) and ionic strength to achieve fast-setting without harmful additives. This substitution fundamentally alters the adhesive system from solvent-based to water-based while maintaining performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a simple, single-container aqueous formulation that eliminates the need for complex two-part mixing systems or expensive specialized equipment. The adhesive is designed for straightforward application and rapid curing, simplifying the overall system without compromising effectiveness.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Object-affected harmful factors

If aqueous-based adhesives are used to eliminate harmful solvents, then environmental safety improves, but setting speed and handling strength deteriorate

Engineering Contradiction:
Improvesolvent contentVSAvoiddry time
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent optimizes multiple parameters simultaneously: pH (3.0-6.5), ionic strength (0.01-0.5 M), and polymer composition to achieve rapid water evaporation and bond formation. The acrylic polymer emulsion is specifically selected and modified to provide fast drying and strength development despite being water-based.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The adhesive is pre-formulated with optimal pH and ionic strength adjustments before application. This preliminary preparation ensures that the adhesive is ready for immediate application and rapid curing without requiring additional on-site mixing or adjustment, thereby reducing overall processing time.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If one-part adhesive formulations are used for simplicity, then ease of operation improves, but storage stability deteriorates due to coagulation and separation

Engineering Contradiction:
Improveapplication simplicityVSAvoidstorage stability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent carefully balances pH (3.0-6.5) and ionic strength to maintain colloidal stability of the acrylic polymer emulsion during storage. This parameter optimization prevents coagulation and separation while maintaining the one-part formulation simplicity. The ionic strength is specifically controlled to stabilize the emulsion without requiring additional stabilizing agents.

Inventive Principle:
Principle #35Parameter changes

4Object-affected harmful factors

If fast-setting aqueous adhesives are developed without coagulants, then user safety improves, but adhesive strength and reliability worsen

Engineering Contradiction:
Improvecoagulant additivesVSAvoidbond strength
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The adhesive system is designed to achieve bonding through self-evaporation of water and natural polymer coalescence without requiring external coagulants or chemical crosslinking agents. The acrylic polymer emulsion is formulated to spontaneously form strong bonds as water evaporates, eliminating the need for additional harmful chemicals while maintaining reliability.

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The adhesive emulsion provides fast-setting bonds with high handling strength, is storage stable, and can be applied from a single container, offering repositionability and re-bondability of substrates, while avoiding the use of harmful additives, thus meeting the industry's demands for environmental and safety considerations.

Implementation Method 1

a polymeric shell with pendent functional groups, which can be externally crosslinked to achieve fast-setting properties

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Implementation Method 2

The adhesive emulsion provides fast-setting bonds with high handling strength

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentUS10221343B2One part, fast-setting, aqueous adhesive emulsions
Publication Date: 2019.03.05 3M INNOVATIVE PROPERTIES CO

AI summary

The present disclosure relates to acrylic adhesive emulsions comprising a core-shell polymeric component comprising an inner core and an outer shell containing at least one pendent functional group; a polyfunctional component capable of reacting with at least one of the pendent functional groups on the outer shell; wherein the inner core is free of functional groups reactive with the pendent functional groups on the outer shell; and wherein the pH of the emulsion is 6.5 or less; and wherein the emulsion is a fast-setting, one part, aqueous, adhesive. Bonded articles made therefrom, and methods of bonding articles using these emulsions are also disclosed.